Word Reading Skill and Brain Anatomy in Adult Resilient Readers Suzanne Welcome 1, Christiana M. Leonard 2, Laura Halderman 1, Stephen Towler 2, & Christine Chiarello 1 University of California, Riverside 1, University of Florida, Gainesville 2

200 university students 7 Divided Visual Field tasks - words presented to left and right hemispheres Structural MRI Woodcock Reading Mastery Tests - Revised –Word Identification –Word Attack –Passage Comprehension Wechsler Abbreviated Scale of Intelligence Handedness preference and performance Biological Substrates for Language Project

Resilient Readers (n=16) Proficient Readers (n=16) Word Attack*18 (10-25) 61 (46-76) Passage Comprehension 64 (45-91) 74 (53-94) Word Identification*39 (18-60) 56 (30-74) Verbal IQ68 (37-96) 70 (37-99) Performance IQ66 (32-86) 68 (27-86) Sex9 male Handedness11 Right-Handed12 Right-Handed * Groups differ significantly (p < 0.01) on this measure

Compensation for Poor Phonological Decoding Stanovich (1980) proposed that deficiencies in lower-level processes like phonological decoding can be compensated for by greater reliance on semantic factors like context Predicts that resilient readers will show normal performance on semantic tasks while showing deficits in other tasks

Study Questions Do resilient readers show behavioral profile consistent with semantic compensation mechanism? Do resilient readers differ in behavioral asymmetry from proficient readers? Do resilient readers differ in brain asymmetry or other aspects of brain anatomy from proficient readers? Do resilient and proficient readers differ in predictors of reading comprehension?

DVF Experiments Pseudoword NamingPronounce pseudowords created by changing single letter of word Word NamingSay presented word Masked Word Recognition2-alternative forced choice of word immediately preceded and followed by mask Lexical DecisionWord/Pseudoword response made by key press Category Member Generation Say an example of presented category (FRUIT – apple) Verb GenerationSay an action associated with presented noun (SCISSORS – cut) Semantic DecisionNatural/Manmade response made by key press

Brain Measures Gray and matter volume of cerebral hemispheres Cerebellar volume Total area and area of sections of corpus callosum Length and asymmetry measures of language- relevant regions –Planum temporale –Planum parietale –Heschl’s gyrus –Pars triangularis –Pars opercularis

DVF Task Results Standard RVF/LH advantage found in both accuracy and reaction time for all 7 tasks –Reading groups did not differ in asymmetry index for any of the seven experimental tasks in either accuracy or RT Groups did not differ in RT on any experimental task Resilient readers less accurate only on tasks that do not require semantic access

* * * Pseudoword Naming Word Naming Lexical Decision Masked Word Recognition Verb Generation Category Generation Semantic Decision

Resilient readers do not differ from proficient readers in any of length, area, volume or asymmetry measures However, relationship between measures and reading ability differs between groups Anatomical Results

Semi-partial r 2 Betat-valueSignif. SES NS Handedness NS Verbal IQ Planum Temporale Asym NS Left pars opercularis length NS White Matter Volume Predicting Passage Comprehension Scores Proficient Readers Resilient Readers White matter volume and verbal IQ account for 66% of variance White matter volume and verbal IQ account for less than 1% of variance Semi-partial r 2 Betat-valueSignif. SES NS Handedness NS Verbal IQ NS Planum Temporale Asym NS Left pars opercularis length NS White Matter Volume NS

R 2 =.482 R 2 =.002 R 2 =.466 R 2 =.089

Summary and Conclusions Do resilient readers show behavioral profile consistent with semantic compensation mechanism? –Resilient readers are less accurate only on tasks that do not require semantic access Do resilient readers differ in behavioral asymmetry from proficient readers? –Resilient readers do not show altered pattern of behavioral asymmetry Do resilient readers differ in brain asymmetry or other aspects of brain anatomy from proficient readers? –Resilient readers do not differ on any measure of brain anatomy Do resilient and proficient readers differ in predictors of reading comprehension? –Proficient readers’ comprehension predicted well by brain volume and verbal IQ; resilient readers’ comprehension not well predicted by any measure

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